NAME

tor - The second-generation onion router

SYNOPSIS

tor [OPTIONvalue]...

DESCRIPTION

tor is a connection-oriented anonymizing communication service. Users
choose a source-routed path through a set of nodes, and negotiate a
"virtual circuit" through the network, in which each node knows its
predecessor and successor, but no others. Traffic flowing down the
circuit is unwrapped by a symmetric key at each node, which reveals the
downstream node.
Basically tor provides a distributed network of servers ("onion
routers"). Users bounce their TCP streams -- web traffic, ftp, ssh, etc
-- around the routers, and recipients, observers, and even the routers
themselves have difficulty tracking the source of the stream.

OPTIONS

-h,-help Display a short help message and exit.
-fFILE
FILE contains further "option value" pairs. (Default:
/etc/tor/torrc)
--hash-password
Generates a hashed password for control port access.
--list-fingerprint
Generate your keys and output your nickname and fingerprint.
--verify-config
Verify the configuration file is valid.
--nt-service--service[install|remove|start|stop] Manage the Tor Windows
NT/2000/XP service. Current instructions can be found at
http://wiki.noreply.org/noreply/TheOnionRouter/TorFAQ#WinNTService
--list-torrc-options
List all valid options.
--version
Display Tor version.
Other options can be specified either on the command-line (--option
value), or in the configuration file (optionvalue). Options
are case-insensitive.
BandwidthRateNbytes|KB|MB|GB|TB
A token bucket limits the average incoming bandwidth usage on
this node to the specified number of bytes per second, and the
average outgoing bandwidth usage to that same value. (Default: 3
MB)
BandwidthBurstNbytes|KB|MB|GB|TB
Limit the maximum token bucket size (also known as the burst) to
the given number of bytes in each direction. This value should
be at least twice your BandwidthRate. (Default: 6 MB)
MaxAdvertisedBandwidthNbytes|KB|MB|GB|TB
If set, we will not advertise more than this amount of bandwidth
for our BandwidthRate. Server operators who want to reduce the
number of clients who ask to build circuits through them (since
this is proportional to advertised bandwidth rate) can thus
reduce the CPU demands on their server without impacting network
performance.
ConnLimitNUM
The minimum number of file descriptors that must be available to
the Tor process before it will start. Tor will ask the OS for as
many file descriptors as the OS will allow (you can find this by
"ulimit -H -n"). If this number is less than ConnLimit, then Tor
will refuse to start.
You probably don’t need to adjust this. It has no effect on
Windows since that platform lacks getrlimit(). (Default: 1000)
ControlPortPort
If set, Tor will accept connections on this port and allow those
connections to control the Tor process using the Tor Control
Protocol (described in control-spec.txt). Note: unless you also
specify one of HashedControlPassword or CookieAuthentication,
setting this option will cause Tor to allow any process on the
local host to control it. This option is required for many Tor
controllers; most use the value of 9051.
ControlListenAddressIP[:PORT]
Bind the controller listener to this address. If you specify a
port, bind to this port rather than the one specified in
ControlPort. We strongly recommend that you leave this alone
unless you know what you’re doing, since giving attackers access
to your control listener is really dangerous. (Default:
127.0.0.1) This directive can be specified multiple times to
bind to multiple addresses/ports.
HashedControlPasswordhashed_password
Don’t allow any connections on the control port except when the
other process knows the password whose one-way hash is
hashed_password. You can compute the hash of a password by
running "tor --hash-password password".
CookieAuthentication0|1
If this option is set to 1, don’t allow any connections on the
control port except when the connecting process knows the
contents of a file named "control_auth_cookie", which Tor will
create in its data directory. This authentication methods
should only be used on systems with good filesystem security.
(Default: 0)
DataDirectoryDIR
Store working data in DIR (Default: /var/lib/tor)
DirServer [nickname] [flags] address:portfingerprint
Use a nonstandard authoritative directory server at the provided
address and port, with the specified key fingerprint. This
option can be repeated many times, for multiple authoritative
directory servers. Flags are separated by spaces, and determine
what kind of an authority this directory is. By default, every
authority is authoritative for current ("v2")-style directories,
unless the "no-v2" flag is given. If the "v1" flags is
provided, Tor will use this server as an authority for old-style
(v1) directories as well. (Only directory mirrors care about
this.) Tor will use this server as an authority for hidden
service information if the "hs" flag is set, or if the "v1" flag
is set and the "no-hs" flag is not set. If a flag "orport=port"
is given, Tor will use the given port when opening encrypted
tunnels to the dirserver. If no dirserver line is given, Tor
will use the default directory servers. NOTE: this option is
intended for setting up a private Tor network with its own
directory authorities. If you use it, you will be
distinguishable from other users, because you won’t believe the
same authorities they do.
FetchHidServDescriptors0|1
If set to 0, Tor will never fetch any hidden service descriptors
from the rendezvous directories. This option is only useful if
you’re using a Tor controller that handles hidserv fetches for
you. (Default: 1)
FetchServerDescriptors0|1
If set to 0, Tor will never fetch any network status summaries
or server descriptors from the directory servers. This option is
only useful if you’re using a Tor controller that handles
directory fetches for you. (Default: 1)
FetchUselessDescriptors0|1
If set to 1, Tor will fetch every non-obsolete descriptor from
the authorities that it hears about. Otherwise, it will avoid
fetching useless descriptors, for example for routers that are
not running. This option is useful if you’re using the
contributed "exitlist" script to enumerate Tor nodes that exit
to certain addresses. (Default: 0)
GroupGID
On startup, setgid to this group.
HttpProxyhost[:port]
Tor will make all its directory requests through this host:port
(or host:80 if port is not specified), rather than connecting
directly to any directory servers.
HttpProxyAuthenticatorusername:password
If defined, Tor will use this username:password for Basic Http
proxy authentication, as in RFC 2617. This is currently the only
form of Http proxy authentication that Tor supports; feel free
to submit a patch if you want it to support others.
HttpsProxyhost[:port]
Tor will make all its OR (SSL) connections through this
host:port (or host:443 if port is not specified), via HTTP
CONNECT rather than connecting directly to servers. You may
want to set FascistFirewall to restrict the set of ports you
might try to connect to, if your Https proxy only allows
connecting to certain ports.
HttpsProxyAuthenticatorusername:password
If defined, Tor will use this username:password for Basic Https
proxy authentication, as in RFC 2617. This is currently the only
form of Https proxy authentication that Tor supports; feel free
to submit a patch if you want it to support others.
KeepalivePeriodNUM
To keep firewalls from expiring connections, send a padding
keepalive cell every NUM seconds on open connections that are in
use. If the connection has no open circuits, it will instead be
closed after NUM seconds of idleness. (Default: 5 minutes)
LogminSeverity[-maxSeverity] stderr|stdout|syslog
Send all messages between minSeverity and maxSeverity to the
standard output stream, the standard error stream, or to the
system log. (The "syslog" value is only supported on Unix.)
Recognized severity levels are debug, info, notice, warn, and
err. We advise using "notice" in most cases, since anything
more verbose may provide sensitive information to an attacker
who obtains the logs. If only one severity level is given, all
messages of that level or higher will be sent to the listed
destination.
LogminSeverity[-maxSeverity] fileFILENAME
As above, but send log messages to the listed filename. The
"Log" option may appear more than once in a configuration file.
Messages are sent to all the logs that match their severity
level.
OutboundBindAddressIP
Make all outbound connections originate from the IP address
specified. This is only useful when you have multiple network
interfaces, and you want all of Tor’s outgoing connections to
use a single one.
PidFileFILE
On startup, write our PID to FILE. On clean shutdown, remove
FILE.
ProtocolWarnings0|1
If 1, Tor will log with severity ’warn’ various cases of other
parties not following the Tor specification. Otherwise, they are
logged with severity ’info’. (Default: 0)
RunAsDaemon0|1
If 1, Tor forks and daemonizes to the background. This option
has no effect on Windows; instead you should use the --service
command-line option. (Default: 0)
SafeLogging0|1
If 1, Tor replaces potentially sensitive strings in the logs
(e.g. addresses) with the string [scrubbed]. This way logs can
still be useful, but they don’t leave behind personally
identifying information about what sites a user might have
visited. (Default: 1)
UserUID
On startup, setuid to this user.
HardwareAccel0|1
If non-zero, try to use crypto hardware acceleration when
available. This is untested and probably buggy. (Default: 0)
AvoidDiskWrites0|1
If non-zero, try to write to disk less frequently than we would
otherwise. This is useful when running on flash memory or other
media that support only a limited number of writes. (Default:
0)
TunnelDirConns0|1
If non-zero, when a directory server we contact supports it, we
will build a one-hop circuit and make an encrypted connection
via its ORPort. (Default: 0)
PreferTunneledDirConns0|1
If non-zero, we will avoid directory servers that don’t support
tunneled directory connections, when possible. (Default: 0)

CLIENTOPTIONS

The following options are useful only for clients (that is, if
SocksPort is non-zero):
AllowInvalidNodesentry|exit|middle|introduction|rendezvous|...
If some Tor servers are obviously not working right, the
directory authorities can manually mark them as invalid, meaning
that it’s not recommended you use them for entry or exit
positions in your circuits. You can opt to use them in some
circuit positions, though. The default is "middle,rendezvous",
and other choices are not advised.
CircuitBuildTimeoutNUM
Try for at most NUM seconds when building circuits. If the
circuit isn’t open in that time, give up on it. (Default: 1
minute.)
CircuitIdleTimeoutNUM
If we have keept a clean (never used) circuit around for NUM
seconds, then close it. This way when the Tor client is entirely
idle, it can expire all of its circuits, and then expire its TLS
connections. Also, if we end up making a circuit that is not
useful for exiting any of the requests we’re receiving, it won’t
forever take up a slot in the circuit list. (Default: 1 hour.)
ClientOnly0|1
If set to 1, Tor will under no circumstances run as a server.
The default is to run as a client unless ORPort is configured.
(Usually, you don’t need to set this; Tor is pretty smart at
figuring out whether you are reliable and high-bandwidth enough
to be a useful server.) (Default: 0)
ExcludeNodesnickname,nickname,...
A list of nodes to never use when building a circuit.
EntryNodesnickname,nickname,...
A list of preferred nodes to use for the first hop in the
circuit. These are treated only as preferences unless
StrictEntryNodes (see below) is also set.
ExitNodesnickname,nickname,...
A list of preferred nodes to use for the last hop in the
circuit. These are treated only as preferences unless
StrictExitNodes (see below) is also set.
StrictEntryNodes0|1
If 1, Tor will never use any nodes besides those listed in
"EntryNodes" for the first hop of a circuit.
StrictExitNodes0|1
If 1, Tor will never use any nodes besides those listed in
"ExitNodes" for the last hop of a circuit.
FascistFirewall0|1
If 1, Tor will only create outgoing connections to ORs running
on ports that your firewall allows (defaults to 80 and 443; see
FirewallPorts). This will allow you to run Tor as a client
behind a firewall with restrictive policies, but will not allow
you to run as a server behind such a firewall. This option is
deprecated; use ReachableAddresses instead.
FirewallPortsPORTS
A list of ports that your firewall allows you to connect to.
Only used when FascistFirewall is set. This option is
deprecated; use ReachableAddresses instead. (Default: 80, 443)
ReachableAddressesADDR[/MASK][:PORT]...
A comma-separated list of IP addresses and ports that your
firewall allows you to connect to. The format is as for the
addresses in ExitPolicy, except that "accept" is understood
unless "reject" is explicitly provided. For example,
’ReachableAddresses 99.0.0.0/8, reject 18.0.0.0/8:80, accept
*:80’ means that your firewall allows connections to everything
inside net 99, rejects port 80 connections to net 18, and
accepts connections to port 80 otherwise. (Default: ’accept
*:*’.)
ReachableDirAddressesADDR[/MASK][:PORT]...
Like ReachableAddresses, a list of addresses and ports. Tor
will obey these restrictions when fetching directory
information, using standard HTTP GET requests. If not set
explicitly then the value of ReachableAddresses is used. If
HttpProxy is set then these connections will go through that
proxy.
ReachableORAddressesADDR[/MASK][:PORT]...
Like ReachableAddresses, a list of addresses and ports. Tor
will obey these restrictions when connecting to Onion Routers,
using TLS/SSL. If not set explicitly then the value of
ReachableAddresses is used. If HttpsProxy is set then these
connections will go through that proxy.
The separation between ReachableORAddresses and
ReachableDirAddresses is only interesting when you are
connecting through proxies (see HttpProxy and HttpsProxy). Most
proxies limit TLS connections (which Tor uses to connect to
Onion Routers) to port 443, and some limit HTTP GET requests
(which Tor uses for fetching directory information) to port 80.
LongLivedPortsPORTS
A list of ports for services that tend to have long-running
connections (e.g. chat and interactive shells). Circuits for
streams that use these ports will contain only high-uptime
nodes, to reduce the chance that a node will go down before the
stream is finished. (Default: 21, 22, 706, 1863, 5050, 5190,
5222, 5223, 6667, 6697, 8300)
MapAddressaddressnewaddress
When a request for address arrives to Tor, it will rewrite it to
newaddress before processing it. For example, if you always want
connections to www.indymedia.org to exit via torserver (where
torserver is the nickname of the server), use "MapAddress
www.indymedia.org www.indymedia.org.torserver.exit".
NewCircuitPeriodNUM
Every NUM seconds consider whether to build a new circuit.
(Default: 30 seconds)
MaxCircuitDirtinessNUM
Feel free to reuse a circuit that was first used at most NUM
seconds ago, but never attach a new stream to a circuit that is
too old. (Default: 10 minutes)
EnforceDistinctSubnets0|1
If 1, Tor will not put two servers whose IP addresses are "too
close" on the same circuit. Currently, two addresses are "too
close" if they lie in the same /16 range. (Default: 1)
RendNodesnickname,nickname,...
A list of preferred nodes to use for the rendezvous point, if
possible.
RendExcludeNodesnickname,nickname,...
A list of nodes to never use when choosing a rendezvous point.
SocksPortPORT
Advertise this port to listen for connections from Socks-
speaking applications. Set this to 0 if you don’t want to allow
application connections. (Default: 9050)
SocksListenAddressIP[:PORT]
Bind to this address to listen for connections from Socks-
speaking applications. (Default: 127.0.0.1) You can also specify
a port (e.g. 192.168.0.1:9100). This directive can be specified
multiple times to bind to multiple addresses/ports.
SocksPolicypolicy,policy,...
Set an entrance policy for this server, to limit who can connect
to the Socks ports. The policies have the same form as exit
policies below.
SocksTimeoutNUM
Let a socks connection wait NUM seconds handshaking, and NUM
seconds unattached waiting for an appropriate circuit, before we
fail it. (Default: 2 minutes.)
TestVianickname,nickname,...
A list of nodes to prefer for your middle hop when building
testing circuits. This option is mainly for debugging
reachability problems.
TrackHostExitshost,.domain,...
For each value in the comma separated list, Tor will track
recent connections to hosts that match this value and attempt to
reuse the same exit node for each. If the value is prepended
with a ’.’, it is treated as matching an entire domain. If one
of the values is just a ’.’, it means match everything. This
option is useful if you frequently connect to sites that will
expire all your authentication cookies (ie log you out) if your
IP address changes. Note that this option does have the
disadvantage of making it more clear that a given history is
associated with a single user. However, most people who would
wish to observe this will observe it through cookies or other
protocol-specific means anyhow.
TrackHostExitsExpireNUM
Since exit servers go up and down, it is desirable to expire the
association between host and exit server after NUM seconds. The
default is 1800 seconds (30 minutes).
UseEntryGuards0|1
If this option is set to 1, we pick a few long-term entry
servers, and try to stick with them. This is desirable because
constantly changing servers increases the odds that an adversary
who owns some servers will observe a fraction of your paths.
(Defaults to 1.)
NumEntryGuardsNUM
If UseEntryGuards is set to 1, we will try to pick a total of
NUM routers as long-term entries for our circuits. (Defaults to
3.)
SafeSocks0|1
When this option is enabled, Tor will reject application
connections that use unsafe variants of the socks protocol --
ones that only provide an IP address, meaning the application is
doing a DNS resolve first. Specifically, these are socks4 and
socks5 when not doing remote DNS. (Defaults to 0.)
TestSocks0|1
When this option is enabled, Tor will make a notice-level log
entry for each connection to the Socks port indicating whether
the request used a safe socks protocol or an unsafe one (see
above entry on SafeSocks). This helps to determine whether an
application using Tor is possibly leaking DNS requests.
(Default: 0)
VirtualAddrNetworkAddress/bits
When a controller asks for a virtual (unused) address with the
MAPADDRESS command, Tor picks an unassigned address from this
range. (Default: 127.192.0.0/10)
When providing proxy server service to a network of computers
using a tool like dns-proxy-tor, change this address to
"10.192.0.0/10" or "172.16.0.0/12". The default
VirtualAddrNetwork address range on a properly configured
machine will route to the loopback interface. For local use, no
change to the default VirtualAddrNetwork setting is needed.
AllowNonRFC953Hostnames0|1
When this option is disabled, Tor blocks hostnames containing
illegal characters (like @ and :) rather than sending them to an
exit node to be resolved. This helps trap accidental attempts
to resolve URLs and so on. (Default: 0)
FastFirstHopPK0|1
When this option is enabled and we aren’t running as a server,
Tor skips the public key step for the first hop of creating
circuits. This is safe since we have already used TLS to
authenticate the server and to establish forward-secure keys.
Turning this option off makes circuit building slower.
(Default: 1)
TransPortPORT
If non-zero, enables transparent proxy support on PORT (by
convention, 9040). Requires OS support for transparent proxies,
such as BSDs’ pf or Linux’s IPTables. If you’re planning to use
Tor as a transparent proxy for a network, you’ll want to examine
and change VirtualAddrNetwork from the default setting. You’ll
also want to set the TransListenAddress option for the network
you’d like to proxy. (Default: 0).
TransListenAddressIP[:PORT]
Bind to this address to listen for transparent proxy
connections. (Default: 127.0.0.1). This is useful for
exporting a transparent proxy server to an entire network.
NATDPortPORT
Allow old versions of ipfw (as included in old versions of
FreeBSD, etc.) to send connections through Tor using the NATD
protocol. This option is only for people who cannot use
TransPort.
NATDListenAddressIP[:PORT]
Bind to this address to listen for NATD connections. (Default:
127.0.0.1).
SERVEROPTIONS
The following options are useful only for servers (that is, if ORPort
is non-zero):
Addressaddress
The IP or fqdn of this server (e.g. moria.mit.edu). You can
leave this unset, and Tor will guess your IP.
AssumeReachable0|1
This option is used when bootstrapping a new Tor network. If set
to 1, don’t do self-reachability testing; just upload your
server descriptor immediately. If AuthoritativeDirectory is also
set, this option instructs the dirserver to bypass remote
reachability testing too and list all connected servers as
running.
ContactInfoemail_address
Administrative contact information for server. This line might
get picked up by spam harvesters, so you may want to obscure the
fact that it’s an email address.
ExitPolicypolicy,policy,...
Set an exit policy for this server. Each policy is of the form
"accept|rejectADDR[/MASK][:PORT]". If /MASK is omitted then
this policy just applies to the host given. Instead of giving a
host or network you can also use "*" to denote the universe
(0.0.0.0/0). PORT can be a single port number, an interval of
ports "FROM_PORT-TO_PORT", or "*". If PORT is omitted, that
means "*".
For example, "accept 18.7.22.69:*,reject 18.0.0.0/8:*,accept
*:*" would reject any traffic destined for MIT except for
web.mit.edu, and accept anything else.
To specify all internal and link-local networks (including
0.0.0.0/8, 169.254.0.0/16, 127.0.0.0/8, 192.168.0.0/16,
10.0.0.0/8, and 172.16.0.0/12), you can use the "private" alias
instead of an address. These addresses are rejected by default
(at the beginning of your exit policy), along with your public
IP address, unless you set the ExitPolicyRejectPrivate config
option to 0. For example, once you’ve done that, you could allow
HTTP to 127.0.0.1 and block all other connections to internal
networks with "accept 127.0.0.1:80,reject private:*", though
that may also allow connections to your own computer that are
addressed to its public (external) IP address. See RFC 1918 and
RFC 3330 for more details about internal and reserved IP address
space.
This directive can be specified multiple times so you don’t have
to put it all on one line.
Policies are considered first to last, and the first match wins.
If you want to _replace_ the default exit policy, end your exit
policy with either a reject *:* or an accept *:*. Otherwise,
you’re _augmenting_ (prepending to) the default exit policy. The
default exit policy is:
reject *:25
reject *:119
reject *:135-139
reject *:445
reject *:465
reject *:563
reject *:587
reject *:1214
reject *:4661-4666
reject *:6346-6429
reject *:6699
reject *:6881-6999
accept *:*
ExitPolicyRejectPrivate0|1
Reject all private (local) networks, along with your own public
IP address, at the beginning of your exit policy. See above
entry on ExitPolicy. (Default: 1)
MaxOnionsPendingNUM
If you have more than this number of onionskins queued for
decrypt, reject new ones. (Default: 100)
MyFamilynickname,nickname,...
Declare that this Tor server is controlled or administered by a
group or organization identical or similar to that of the other
named servers. When two servers both declare that they are in
the same ’family’, Tor clients will not use them in the same
circuit. (Each server only needs to list the other servers in
its family; it doesn’t need to list itself, but it won’t hurt.)
Nicknamename
Set the server’s nickname to ’name’. Nicknames must be between 1
and 19 characters inclusive, and must contain only the
characters [a-zA-Z0-9].
NumCPUsnum
How many processes to use at once for decrypting onionskins.
(Default: 1)
ORPortPORT
Advertise this port to listen for connections from Tor clients
and servers.
ORListenAddressIP[:PORT]
Bind to this IP address to listen for connections from Tor
clients and servers. If you specify a port, bind to this port
rather than the one specified in ORPort. (Default: 0.0.0.0) This
directive can be specified multiple times to bind to multiple
addresses/ports.
PublishServerDescriptor0|1
If set to 0, Tor will act as a server if you have an ORPort
defined, but it will not publish its descriptor to the
dirservers. This option is useful if you’re testing out your
server, or if you’re using a Tor controller that handles
directory publishing for you. (Default: 1)
RedirectExitpatterntarget
Whenever an outgoing connection tries to connect to one of a
given set of addresses, connect to target (an address:port pair)
instead. The address pattern is given in the same format as for
an exit policy. The address translation applies after exit
policies are applied. Multiple RedirectExit options can be
used: once any one has matched successfully, no subsequent rules
are considered. You can specify that no redirection is to be
performed on a given set of addresses by using the special
target string "pass", which prevents subsequent rules from being
considered.
ShutdownWaitLengthNUM
When we get a SIGINT and we’re a server, we begin shutting down:
we close listeners and start refusing new circuits. After NUM
seconds, we exit. If we get a second SIGINT, we exit
immediately. (Default: 30 seconds)
AccountingMaxNbytes|KB|MB|GB|TB
Never send more than the specified number of bytes in a given
accounting period, or receive more than that number in the
period. For example, with AccountingMax set to 1 GB, a server
could send 900 MB and receive 800 MB and continue running. It
will only hibernate once one of the two reaches 1 GB. When the
number of bytes is exhausted, Tor will hibernate until some time
in the next accounting period. To prevent all servers from
waking at the same time, Tor will also wait until a random point
in each period before waking up. If you have bandwidth cost
issues, enabling hibernation is preferable to setting a low
bandwidth, since it provides users with a collection of fast
servers that are up some of the time, which is more useful than
a set of slow servers that are always "available".
AccountingStartday|week|month [day] HH:MM
Specify how long accounting periods last. If month is given,
each accounting period runs from the time HH:MM on the dayth day
of one month to the same day and time of the next. (The day
must be between 1 and 28.) If week is given, each accounting
period runs from the time HH:MM of the dayth day of one week to
the same day and time of the next week, with Monday as day 1 and
Sunday as day 7. If day is given, each accounting period runs
from the time HH:MM each day to the same time on the next day.
All times are local, and given in 24-hour time. (Defaults to
"month 1 0:00".)
ServerDNSResolvConfFilefilename
Overrides the default DNS configuration with the configuration
in filename. The file format is the same as the standard Unix
"resolv.conf" file (7). This option, like all other ServerDNS
options, only affects name lookup that your server does on
behalf of clients. Also, it only takes effect if Tor was built
with eventdns support. (Defaults to use the system DNS
configuration.)
ServerDNSSearchDomains0|1
If set to 1, then we will search for addresses in the local
search domain. For example, if this system is configured to
believe it is in "example.com", and a client tries to connect to
"www", the client will be connected to "www.example.com". This
option only affects name lookup that your server does on behalf
of clients, and only takes effect if Tor was build with eventdns
support. (Defaults to "0".)
ServerDNSDetectHijacking0|1
When this option is set to 1, we will test periodically to
determine whether our local nameservers have been configured to
hijack failing DNS requests (usually to an advertising site).
If they are, we will attempt to correct this. This option only
affects name lookup that your server does on behalf of clients,
and only takes effect if Tor was build with eventdns support.
(Defaults to "1".)
ServerDNSTestAddressesaddress,address,...
When we’re detecting DNS hijacking, make sure that these valid
addresses aren’t getting redirected. If they are, then our DNS
is completely useless, and we’ll reset our exit policy to
"reject *:*". This option only affects name lookup that your
server does on behalf of clients, and only takes effect if Tor
was build with eventdns support. (Defaults to "www.google.com,
www.mit.edu, www.yahoo.com, www.slashdot.org".)
ServerDNSAllowNonRFC953Hostnames0|1
When this option is disabled, Tor does not try to resolve
hostnames containing illegal characters (like @ and :) rather
than sending them to an exit node to be resolved. This helps
trap accidental attempts to resolve URLs and so on. This option
only affects name lookup that your server does on behalf of
clients, and only takes effect if Tor was build with eventdns
support. (Default: 0)

DIRECTORYSERVEROPTIONS

The following options are useful only for directory servers (that is,
if DirPort is non-zero):
AuthoritativeDirectory0|1
When this option is set to 1, Tor operates as an authoritative
directory server. Instead of caching the directory, it
generates its own list of good servers, signs it, and sends that
to the clients. Unless the clients already have you listed as a
trusted directory, you probably do not want to set this option.
Please coordinate with the other admins at tor-ops@freehaven.net
if you think you should be a directory.
V1AuthoritativeDirectory0|1
When this option is set in addition to AuthoritativeDirectory,
Tor also generates a version 1 directory (for Tor clients up to
0.1.0.x). (As of Tor 0.1.1.12 every (v2) authoritative
directory still provides most of the v1 directory functionality,
even without this option set to 1. This however is expected to
change in the future.)
VersioningAuthoritativeDirectory0|1
When this option is set to 1, Tor adds information on which
versions of Tor are still believed safe for use to the published
directory. Each version 1 authority is automatically a
versioning authority; version 2 authorities provide this service
optionally. See RecommendedVersions, RecommendedClientVersions,
and RecommendedServerVersions.
NamingAuthoritativeDirectory0|1
When this option is set to 1, then the server advertises that it
has opinions about nickname-to-fingerprint bindings. It will
include these opinions in its published network-status pages, by
listing servers with the flag "Named" if a correct binding
between that nickname and fingerprint has been registered with
the dirserver. Naming dirservers will refuse to accept or
publish descriptors that contradict a registered binding. See
approved-routers in the FILES section below.
HSAuthoritativeDir0|1
When this option is set in addition to AuthoritativeDirectory,
Tor also accepts and serves hidden service descriptors.
(Default: 0)
DirPortPORT
Advertise the directory service on this port.
DirListenAddressIP[:PORT]
Bind the directory service to this address. If you specify a
port, bind to this port rather than the one specified in
DirPort. (Default: 0.0.0.0) This directive can be specified
multiple times to bind to multiple addresses/ports.
DirPolicypolicy,policy,...
Set an entrance policy for this server, to limit who can connect
to the directory ports. The policies have the same form as exit
policies above.
RecommendedVersionsSTRING
STRING is a comma-separated list of Tor versions currently
believed to be safe. The list is included in each directory, and
nodes which pull down the directory learn whether they need to
upgrade. This option can appear multiple times: the values from
multiple lines are spliced together. When this is set then
VersioningAuthoritativeDirectory should be set too.
RecommendedClientVersionsSTRING
STRING is a comma-separated list of Tor versions currently
believed to be safe for clients to use. This information is
included in version 2 directories. If this is not set then the
value of RecommendedVersions is used. When this is set then
VersioningAuthoritativeDirectory should be set too.
RecommendedServerVersionsSTRING
STRING is a comma-separated list of Tor versions currently
believed to be safe for servers to use. This information is
included in version 2 directories. If this is not set then the
value of RecommendedVersions is used. When this is set then
VersioningAuthoritativeDirectory should be set too.
DirAllowPrivateAddresses0|1
If set to 1, Tor will accept router descriptors with arbitrary
"Address" elements. Otherwise, if the address is not an IP or is
a private IP, it will reject the router descriptor. Defaults to
0.
AuthDirBadExitAddressPattern...
Authoritative directories only. A set of address patterns for
servers that will be listed as bad exits in any network status
document this authority publishes, if AuthDirListBadExits is
set.
AuthDirInvalidAddressPattern...
Authoritative directories only. A set of address patterns for
servers that will never be listed as "valid" in any network
status document that this authority publishes.
AuthDirRejectAddressPattern...
Authoritative directories only. A set of address patterns for
servers that will never be listed at all in any network status
document that this authority publishes, or accepted as an OR
address in any descriptor submitted for publication by this
authority.
AuthDirListBadExits0|1
Authoritative directories only. If set to 1, this directory has
some opinion about which nodes are unsuitable as exit nodes.
(Do not set this to 1 unless you plan to list nonfunctioning
exits as bad; otherwise, you are effectively voting in favor of
every declared exit as an exit.)
AuthDirRejectUnlisted0|1
Authoritative directories only. If set to 1, the directory
server rejects all uploaded server descriptors that aren’t
explicitly listed in the fingerprints file. This acts as a
"panic button" if we get Sybiled. (Default: 0)

HIDDENSERVICEOPTIONS

The following options are used to configure a hidden service.
HiddenServiceDirDIRECTORY
Store data files for a hidden service in DIRECTORY. Every
hidden service must have a separate directory. You may use this
option multiple times to specify multiple services.
HiddenServicePortVIRTPORT [TARGET]
Configure a virtual port VIRTPORT for a hidden service. You may
use this option multiple times; each time applies to the service
using the most recent hiddenservicedir. By default, this option
maps the virtual port to the same port on 127.0.0.1. You may
override the target port, address, or both by specifying a
target of addr, port, or addr:port.
HiddenServiceNodesnickname,nickname,...
If possible, use the specified nodes as introduction points for
the hidden service. If this is left unset, Tor will be smart and
pick some reasonable ones; most people can leave this unset.
HiddenServiceExcludeNodesnickname,nickname,...
Do not use the specified nodes as introduction points for the
hidden service. In normal use there is no reason to set this.
PublishHidServDescriptors0|1
If set to 0, Tor will run any hidden services you configure, but
it won’t advertise them to the rendezvous directory. This option
is only useful if you’re using a Tor controller that handles
hidserv publishing for you. (Default: 1)
RendPostPeriodNseconds|minutes|hours|days|weeks
Every time the specified period elapses, Tor uploads any
rendezvous service descriptors to the directory servers. This
information is also uploaded whenever it changes. (Default: 20
minutes)

SIGNALS

Tor catches the following signals:
SIGTERM
Tor will catch this, clean up and sync to disk if necessary, and
exit.
SIGINT Tor clients behave as with SIGTERM; but Tor servers will do a
controlled slow shutdown, closing listeners and waiting 30
seconds before exiting. (The delay can be configured with the
ShutdownWaitLength config option.)
SIGHUP The signal instructs Tor to reload its configuration (including
closing and reopening logs), fetch a new directory, and kill and
restart its helper processes if applicable.
SIGUSR1
Log statistics about current connections, past connections, and
throughput.
SIGUSR2
Switch all logs to loglevel debug. You can go back to the old
loglevels by sending a SIGHUP.
SIGCHLD
Tor receives this signal when one of its helper processes has
exited, so it can clean up.
SIGPIPE
Tor catches this signal and ignores it.
SIGXFSZ
If this signal exists on your platform, Tor catches and ignores
it.

FILES

/etc/tor/torrc
The configuration file, which contains "option value" pairs.
/var/lib/tor/
The tor process stores keys and other data here.
DataDirectory/cached-status/*
The most recently downloaded network status document for each
authority. Each file holds one such document; the filenames are
the hexadecimal identity key fingerprints of the directory
authorities.
DataDirectory/cached-routers and cached-routers.new
These files hold downloaded router statuses. Some routers may
appear more than once; if so, the most recently published
descriptor is used. The ".new" file is an append-only journal;
when it gets too large, all entries are merged into a new
cached-routers file.
DataDirectory/state
A set of persistent key-value mappings. These are documented in
the file. These include:
- The current entry guards and their status.
- The current bandwidth accounting values (unused so far; see
below).
- When the file was last written
- What version of Tor generated the state file
- A short history of bandwidth usage, as produced in the router
descriptors.
DataDirectory/bw_accounting
Used to track bandwidth accounting values (when the current
period starts and ends; how much has been read and written so
far this period). This file is obsolete, and the data is now
stored in the ’state’ file as well. Only used when bandwidth
accounting is enabled.
DataDirectory/control_auth_cookie
Used for cookie authentication with the controller. Regenerated
on startup. See control-spec.txt for details. Only used when
cookie authentication is enabled.
DataDirectory/keys/*
Only used by servers. Holds identity keys and onion keys.
DataDirectory/fingerprint
Only used by servers. Holds the fingerprint of the server’s
identity key.
DataDirectory/approved-routers
Only for naming authoritative directory servers (see
NamingAuthoritativeDirectory). This file lists nickname to
identity bindings. Each line lists a nickname and a fingerprint
separated by whitespace. See your fingerprint file in the
DataDirectory for an example line. If the nickname is !reject
then descriptors from the given identity (fingerprint) are
rejected by this server. If it is !invalid then descriptors are
accepted but marked in the directory as not valid, that is, not
recommended.
HiddenServiceDirectory/hostname
The <base32-encoded-fingerprint>.onion domain name for this
hidden service.
HiddenServiceDirectory/private_key
The private key for this hidden service.